The body in pilot whales is robust, with a deep tail stock. The
melon is exaggerated and bulbous and the beak is barely discernible
or non-existent. The dorsal fin is wide, broad- based, falcate and
set well forward on the body. The flippers are long, slender, and
sickle-shaped.
A faint grey saddle patch may be visible behind the dorsal fin.
A grey midventral line extends to the front into an anchor-shaped
chest patch and widens posteriorily to a genital patch. The short-finned
pilot whale has a shorter and wider skull than the long-finned species,
with the pre-maxillae covering the maxillary bones (Olson, 2009),

Long- and short-finned pilot whales (G. melas and G.
macrorhynchus) are difficult to distinguish at sea. However,
the species differ, as the name suggests, in flipper length, skull
shape and number of teeth. On average, the pectoral fins of the
short-finned pilot whales are 1/6 the body length (Olson, 2009).
Adult females reach a body length of approx. 5.5 m and males 7.2
m, with a body weight of up to 3,200 kg (Jefferson et al., 2008).

G. macrohynchus appears to vary geographically, but no comprehensive
study has been undertaken. Off the Pacific coast of Japan, a northern
and a southern population differ sharply in colour pattern and in
body size and shape and also in cranial features. However, their
taxonomic status remains unsettled (Rice, 1998 and refs. therein;
Olson and Reilly, 2002). Water temperature seems to be the primary
factor determining the relative distributions of these two populations
(Fullard et al. 2000).

2. Distribution

Short-finned pilot whales are found in deep offshore areas and
usually do not range north of 50°N or south of 40°S (Jefferson
et al. 1993). There is some overlap in range between the two species
(Olson, 2009). G. macrorhynchus is probably circumglobal
in tropical and warm temperate waters. In the Atlantic it ranges
north to New Jersey and to Charente-Maritime in France (it is not
present in the Mediterranean); in the Pacific, its range extends
north into cooler temperate waters as far as Hokkaido (50°N,
145°W), and Vancouver Island. It is vagrant to the Alaska Peninsula
(57°N, 156°W). The southern limits of the range are not
fully determined due to past confusion with the G. melas,
but G. macrohynchus is known to range south to São
Paulo, Cape Province, Western Australia, Tasmania, and Cape Farewell
on North Island in New Zealand (Rice, 1998). There is an hypothesis
that the short-finned pilot whale is in the process of expanding
to fill the former range of long-finned pilot whales in the North
Pacific (Bernard and Reilly, 1999 and refs. therein).

Olson (2009) summarized population estimates obtained from various
researchers via line-transect methods between the 1990's and 2005.
In the western Pacific off Northern Japan, the population amounts
to 5,300, whereas off southern Japan numbers reach 53,608 (Miyashita,
1993 in Olson, 2009). Dolar (1999) estimated a total of 7,700 individuals
in the eastern Sulu Sea (Philippines). Around Hawaii, 8,806 were
estimated (Barlow, 2006) and in the Eastern tropical Pacific, the
most recent estimate from 2000 gives 589,000 (CV=0,26), with a significant
increase of abundance estimates from 1986-1990 to 1998-2000 (Gerrodette
and Forcada, 2002). In the US Golf of Mexico, Waring et al. (2007)
estimated 2,388, and their best estimate for the western North Atlantic
stock is 31,139 whales (CV=0,27). Tenerife's (Spain) resident population
of G. macrorhynchus is estimated at 350 individuals (Glen, 2003).
However, the current population trend in the Atlantic Ocean is unknown.

4. Biology and Behaviour

Behaviour: Hindell (2008) used sophisticated telemetry logging
devices to show that short-finned pilot whales employ energetic
sprints to chase down their deep-dwelling prey. These sprints are
costly in terms of energy and therefore oxygen, which has to be
taken into account in foraging models. Baird et al. (2003), using
suction-cup attached time-depth recorders (TDRs) and video camera
systems (Crittercam), recorded deep dives at dusk and dawn following
vertically migrating prey, and near-surface foraging at night,.
The deepest dives recorded (typically 600-800m, max. 27 minutes)
were during the day. At night, all whales dove regularly to between
300 and 500m, and the rate of deep (>100m) dives at night was
almost four times greater than during the day. Long bouts of shallow
(<100 m) diving occurred only during the day. Video footage from
the Crittercams during these shallow dive bouts indicated the whales
were engaged in social, rest and travel behaviours, but no feeding
was documented. Dive-depth differences between day and night presumably
reflect vertically migrating prey, though the prey is concentrated
at depths of 300-50m during the night.

Habitat: The species prefers deep water and occurs mainly
at the edge of the continental shelf and over deep submarine canyons
(Carwardine, 1995). Davis et al. (1998) found that G. macrorhynchus
in the Gulf of Mexico preferred water depths between 600 and 1,000
m.

Schooling: Pods of up to several hundred short-finned pilot
whales have been reported, and members of this highly social species
are almost never seen alone. Strong social bonds may partially explain
why pilot whales are among the species of cetaceans that most frequently
mass-strand. Although detailed studies of behaviour have only begun
recently, pilot whales appear to live in relatively stable female-based
groups (Jefferson et al. 1993).

Three types of social organisation for pilot whale pods off southern
California were described: travelling/hunting groups, feeding groups,
and loafing groups. The travelling/ hunting groups have also been
appropriately described as "chorus lines" as the animals
in these are oriented in a broad rank of up to 2 miles in width,
but only a few animals deep. Sexual and age-class segregation also
have been observed in chorus lines. In the second type of group
described, the feeding group, there was sometimes general movement
of whales in a given direction, but individuals tend to remain fairly
independent of one another. The third type of pod, the "loafing
group", was described as an almost stationary aggregation of
12-30 or more individuals, floating at the surface, nearly or actually
touching one another. A wide variety of types of behaviour, including
mating, was reported to occur in loafing groups (Bernard and Reilly,
1999 and refs. therein).

In the eastern tropical Pacific, approximately 15% of pilot whale
sightings include other cetaceans. They are sighted with bottlenose
dolphins (Tursiops truncatus) and with tuna-dolphin aggregations
(Thunnus albacares and Stenella spp.) and S. coeruleoalba. The most
common associate in coastal waters is the common bottlenose dolphin;
pilot whales have been sighted also with short-beaked common dolphins
(Delphinus delphis), Pacific white-sided dolphins (Lagenorhynchus
obliquidens), gray whales (Eschrichtius robustus), fin and sperm
whales (Balaenoptera physalus and Physeter catodon) and killer whales
(Orcinus orca; Bernard and Reilly, 1999 and refs. therein).

Mazzuca et al. (1999) found that in the Hawaiian Archipelago, short-finned
pilot whales stranded in the largest groups and experienced the
greatest number of stranding events (x= 14 animals, 5 events) of
all cetaceans recorded from 1957 through 1998. The greatest incidence
of odontocete mass strandings occurred on the Island of Maui during
the month of June. Mass strandings occurred on all the high Hawaiian
Islands, except Hawaii; none were reported on the islands or atolls
northwest of Kauai. Two-thirds of the events occurred on the leeward
sides of the islands with similar bottom topography, coastal configuration,
and geomagnetic characteristics in all events.

Mignucci et al. (1999) reported that in waters off Puerto Rico and
the US and British Virgin Islands, short-finned pilot whales were
one of the most frequently stranded species. A high number of strandings
occur in the winter and spring.

Food:l Although they also take fish, pilot whales are thought
to be primarily adapted to feeding on squid (Hacker, 1992). They
show the tooth reduction typical of other squid-eating cetaceans
(Jefferson et al., 1993). Hernandez-Garcia and Martin (1994) found
that stomach contents of two short-finned pilot whales found on
the Canary Islands were made up entirely of cephalopods: Todarodes
sagittatus, Cranchia and juveniles of Megalocranchia.

Mintzer et al. (2008) examined the stomach contents of short-finned
pilot whales from the North Carolina coast in January 2005. Brachioteuthis
riisei (numerical abundance 28%), an oceanic species, was the
most important cephalopod prey, but Taonius pavo (12%) and
Histioteuthis reversa (9%) also represented a substantial
part of the diet. A large number of otoliths belonging to the fish
Scopelogadus beanii were present (25%), indicating that the
whales fed primarily off the continental shelf prior to stranding.
Stomach content composition differed from those of short-finned
pilot whales from the Pacific coast in which neritic species dominate
the diet. These findings also suggest that there is a considerable
difference between the diet of short- and long-finned pilot whales
(Globicephala melas) in the western North Atlantic. The latter
feed predominantly on the long-finned squid (Loligo pealei),
whereas the former feed on deep-water species.

Reproduction: Females become post-reproductive at around
35 years but may continue to suckle young for up to 15 additional
years, suggesting a complex social structure in which older females
may give their own or related calves a "reproductive edge"
through prolonged suckling. Calving peaks occur in spring and autumn
in the Southern Hemisphere and vary by stock in the Northern Hemisphere
(Jefferson et al. 1993).

5. Migration

The species appears to be generally nomadic, with no fixed migrations,
but some north-south movements are related to prey movements or
incursions of warm water. Inshore-offshore movements are determined
by spawning squid (outside the squid season, G. macrorhynchus is
usually found offshore). Some populations are present year-round,
such as in Hawaii and the Canary Islands (Carwardine, 1995).
.
A marked seasonality in the distribution of pilot whales has been
observed in at least three areas: off southern California; in the
eastern tropical Pacific; and off the coast of Japan. In southern
California, the seasonal abundance of pilot whales appears to be
correlated with the seasonal abundance of spawning squid. E.g. during
years of low squid abundance, fewer pilot whales were sighted near
Catalina Island. In both the coastal and pelagic waters of the eastern
tropical Pacific, the density of population centres appears to change
seasonally in response to major changes in the current structure
of the area. In the southern California Bight, the occurrence of
short-finned pilot whales was associated with high relief topography.
There seems to also be a seasonal distribution with depth: pilot
whales were found in significantly shallower water during winter
(depth 375m) than summer (800m) (Bernard and Reilly, 1999 and refs.
therein).

There have been no systematic studies of home range or migration
of individuals of this genus. Opportunistic observations in the
southern California Bight have indicated that a pod of 20-30 individuals,
identified by scars, unusual marks, etc., lived in the area year-round
in the 1970's. Following the strong El Niño event in 1982-83,
subsequent surveys throughout the 1980s turned up few sightings,
and documented the absence of all but one pod of pilot whales near
Catalina Island. Shipboard surveys along the entire California coast
using line-transect methodology were conducted in 1991 and 1993
within 550km of shore, documenting an apparent return of this stock.
The calculated abundance estimate was 1,004 individuals (Shane,
1995; Bernard and Reilly, 1999 and refs. therein).

6. Threats

Direct catch: The short-finned pilot whale has been exploited
for centuries in the western North Pacific. The largest catches
have occurred off Japan, where small coastal whaling stations and
drive fisheries took a few hundred annually (Jefferson et al. 1993).
Between 1982 and 1985, 519 of the northern form and 1,755 whales
of the southern form were killed. From 1985 to 1989, Japan took
a total of 2,326 short-finned pilot whales. This fishery is ongoing:
In 1997, Japan recorded a catch of 347 short-finned pilot whales
(Olson and Reilly, 2002), which was reduced to 63 specimens in 2004
(Olson, 2009). The current national quota is 50 (Taylor et al. 2008).

Elsewhere, a small, intermittently active fishery takes around 220
pilot whales per year in the Lesser Antilles in the Caribbean at
St. Vincent Island, and there are indications of a small fishery
at St. Lucia Island (Bernard and Reilly, 1999 and refs. therein).
Dolar et al. (1994) reported on illegal fisheries for marine mammals
in central and southern Visayas, northern Mindanao and Palawan,
Philippines, where hunters took dolphins and short-finned pilot
whales for bait or human consumption. These are taken by hand harpoons
or, increasingly, by togglehead harpoon shafts shot from modified,
rubber-powered spear guns. Around 800 cetaceans were taken annually.

Incidental catch: There are probably more pilot whales taken
incidentally than is presently documented. In US Atlantic waters,
pilot whales have been taken in a variety of fisheries, but not
exceeding the allowable annual take under US law (Olson, 2009).
Based on preliminary data, the squid round-haul fishery in southern
California waters is estimated to have taken 30 short-finned pilot
whales in one year.

In the California drift gill net fishery between 1993 and 1995,
the mean annual take of short-finned pilot whales was 20 (Bernard
and Reilly, 1999 and refs. therein). Since the take in US waters
exceeded the allowable limit, a take reduction plan was implemented,
and currently the annual take is lower than the allowable limit
(Olson, 2009).

Forney and Kobayashi (2007) reported two catches in 24,542 observed
sets in the Hawaii-based longline fishery, corresponding to about
1-2 casualties per year in this fishery.
In the western Pacific ocean, an estimated 350-750 G. macrorhynchus
die annually in passive nets and traps set in Japanese fisheries
(Bernard and Reilly, 1999 and refs. therein).

Systematic surveys of 'whalemeat' markets in the Republic of (South)
Korea (Baker et al., 2006) using molecular monitoring also revealed
products from short-finned pilot whales. As Korea has no programme
of commercial or scientific whaling and there is a closure on the
hunting of dolphins and porpoises, the only legal source of these
products was assumed to be incidental fisheries mortality ('bycatch')
as reported by the government to the International Whaling Commission.

In the Caribbean, the most common human-related cause of death categories
off Puerto Rico and the US and British Virgin Islands were entanglement
and accidental captures, followed by animals being shot or speared
(Mignucci et al. 1999).

Pollution: There is a wide variation in contaminant loads
in short-finned pilot whales. High concentrations of DDT and PCB
were found in whales off the Pacific coast of the USA in the mid
70s, while low levels were found in whales from the Antilles and
off Japan (Bernard and Reilly, 1999 and refs. therein). The latter
is confirmed by Bustamante et al. (2003), who investigated trace
element concentrations in liver, muscle and blubber tissues of two
short-finned pilot whales in New Caledonia in the southwestern Pacific
and found that values for Al, Cd, Co, Cr, Cu, Fe, organic and total
Hg, Mn, Ni, Se, V, and Zn were below levels for concern.

Tourism: The presence of whale watching vessels can potentially
cause short-term disturbance in the natural behaviours of several
cetacean species. Glen (2003) found a significant difference between
the number of vessels around a pod correlated with whale watching,
and G. macrorhynchus avoidance behaviour has been observed in waters
off Tenerife, Spain. In the presence of one or two vessels, 28% of
sightings involved avoidance behaviours, rising to 62% of sightings
in the presence of three or more vessels. The author concludes that
any impacts from whale watching vessels should be minimised until
it is shown that they are not detrimental to the status of the population.

G. macrorhynchus is listed as "Data Deficient"
by the IUCN, and world-wide only one population, off northern Japan,
is currently considered at risk. Insufficient information is available
to accurately evaluate the species' status elsewhere (Stacey and
Baird, 1994). The species is listed on Appendix II of CITES.

For recommendations on South American stocks, see Hucke-Gaete (2000)
(see Appendix 1). See also general
recommendations on Southeast Asian stocks in Perrin et al. (1996;
Appendix 2).

This species is not listed by CMS, but inclusion in Appendix II
is recommended. Recent results indicate a marked seasonality in
the distribution of pilot whales in at least three areas: off southern
California; in the eastern tropical Pacific; and off the coast of
Japan. Range states concerned are the US, Mexico, Guatemala, El
Salvador, Honduras, Nicaragua, Costa Rica, Panama, Columbia, Ecuador
and Peru, as well as Russia, Japan, North and South Korea and China.